The present invention relates to a coating apparatus, for coating a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display device with resist, a heat resistant coating material, a liquid crystal or a polyimide used as an orienting film, as well as to a discharge means, and a coating method.
It is known to form a thin film on a substrate surface and to etch this thin film. For example, when forming a circuit pattern on a substrate such as a semiconductor wafer made of Si, a resist is applied to the substrate, and processes such as exposure, development, and etching are sequentially and repeatedly performed.
A resist is applied to the substrate generally by spin coating. In spin coating, the resist is dropped onto near the center of the substrate rotating at a high speed. The resist spreads over the entire surface of the substrate, and extra resist is removed as it is shaken off to the outside by the centrifugal force. This is how the resist is applied to the entire surface of the substrate.
In the above spin coating process, since the resist is shaken off to the outside by the centrifugal force, the resist is not utilized efficiently as the material. More specifically, in spin coating, the material utilization of the resist is as low as about 1% to 10%, and most of the resist is actually wastefully exhausted as a waste liquor.
In spin coating, a resist film also forms on the outer periphery of the substrate. As the substrate is transferred between the respective processes, its outer periphery is rubbed to produce resist dust. Hence, a solvent is applied to the outer periphery of the substrate by a nozzle to remove the resist film formed there. Accordingly, a process for removing the resist from the outer periphery is required, leading to a cumbersome operation.
It is an object of the present invention to provide a coating apparatus, discharge means, and coating method with which a film having a uniform thickness can be formed and the material utilization is improved.
According to the present invention, there is provided a coating apparatus for forming a film on a surface of an object to be coated such as a substrate, comprising: holding means for holding the substrate; discharge means, containing a coating solution and formed with a plurality of discharge holes at a portion thereof opposing the object to be coated, for discharging the coating solution; fine-vibration means for applying fine vibrations to discharge the coating solution; and driving means for driving the holding means and the discharge means relative to each other.
According to the present invention, the coating solution is applied to the object to be coated by controlling its discharge amount by the fine-vibration means in accordance with fine vibration control while driving to rotate the object to be coated by the driving means. Thus, the coating solution can be applied to the object to be coated by uniforming its coating mount with the fine-vibration means. The coating operation is less limited by the shape of the surface of the object to be coated. Furthermore, the coating solution can be suppressed from being applied to a portion where coating is unnecessary.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.